1. Technical Field
This invention generally relates to enlarging a hole in a substrate such that the enlarged hole is centered on the existing hole. Specifically, this invention refers to knock-out dies for enlarging the holes formed by knock-outs or slugs in an electrical box, and to an apparatus and method for centering the enlarged holes relative to the existing knock-out holes.
2. State of the Art
Knock-out dies with centering capability are provided by a centering element integral with the blade or punch of the die. These dies may be used to replace non-centering dies for users that wish to upgrade from their non-centering dies.